Experimentálne stanovenie únavového vrubového súčiniteľa napätia pre vzorky z ocele s355 zvárané technológiou MIG

Joining components by welding is the most widespread method of joining for metal structures. For this reason, fatigue strength assessment of welded joints is of great interest to engineers involved in structure design. The welded joint itself can be considered a notch composed of a technological (inner deffects and material inhomogenities) and a geometrical (surface irregularities) part. Due to stress and strain concentration, such a notch decreases fatigue endurance of a welded construction. This paper shows experimental quantification of the fatigue stress notch factor for butt welded joints manufactured by MIG technology.Technológia zvárania je pri kovových konštrukciách najrozšírenejšou metódou spájania konštrukčných častí. Z tohto dôvodu je problematike posudzovania únavovej životnosti zvarových spojov venovaná zvýšená pozornosť strojných inžinierov. Na zvar ako taký možno pozerať ako na vrub pozostávajúci z technologickej (vnútorné chyby a nehomogenity materiálu) a geometrickej (povrchová členitosť) časti. Tento vrub vplyvom koncentrácie napätia a deformácie znižuje únavovú odolnosť konštrukcie. Obsahom tohoto príspevku je kvantifikácia únavového vrubového súčiniteľa napätia pre tupý zvar vyhotovený technológiou MIG

Multiaxial fatigue criterion based on parameters from torsion and axial S-N curve

Multiaxial high cycle fatigue is a topic that concerns nearly all industrial domains. In recent years, a great deal of recommendations how to address problems with multiaxial fatigue life time estimation have been made and a huge progress in the field has been achieved. Until now, however, no universal criterion for multiaxial fatigue has been proposed. Addressing this situation, this paper offers a design of a new multiaxial criterion for high cycle fatigue. This criterion is based on critical plane search. Damage parameter consists of a combination of normal and shear stresses on a critical plane (which is a plane with maximal shear stress amplitude). Material parameters used in proposed criterion are obtained from torsion and axial S-N curves. Proposed criterion correctly calculates life time for boundary loading condition (pure torsion and pure axial loading). Application of proposed model is demonstrated on biaxial loading and the results are verified with testing program using specimens made from S355 steel. Fatigue material parameters for proposed criterion and multiple sets of data for different combination of axial and torsional loading have been obtained during the experiment

Relationships between production, quality of milk and udder health status of ewes during machine milking

The chosen traits of production, composition and quality of milk (analysis of 255 milk samples) were evaluated in ewes on the 1st to 3rd lactation (n=64) during milking period (4 control measurements – CM) and in the machine milking conditions. Udder health status of the ewes (UHS; n=255) was evaluated by means of 5 point linear scale subjectively at the same time. The ewes of three pure breeds (Tsigai – T, Improved Valachian – IV and Lacaune – LC) and two crossbreds (TxLC and IVxLC) were involved in the experiment. The machine milked milk (milk production) at CM (0.462 kg), the proportion of machine stripped milk (25.19 %) and also UHS (1.65) were significantly affected by the genotype group (P0.05 respectively)

Performance of chosen multiaxial cycle counting method under non-proportional multiaxial variable loading.

One of the most crucial tasks in fatigue life-time estimation of components loaded with multiaxial variable amplitude loading is to correctly identify loading cycles that can be used with multiaxial damage criterions. During past years, several cycle counting methods have been proposed for multiaxial loading conditions. The aim of this text is the comparison of selected multiaxial cycle counting methods, namely Wang-Brown’s method, Modified Wang-Brown’s method, Bannantine-Socie’s method and then a critical analysis of the obtained results. For the comparison of chosen methods, a new data set, consisting of experimentally obtained results from multiaxial non-proportional variable amplitude loading tests carried on by authors, has been used. The tested specimens were made from S355J0 structural steel and the testing procedure has been carried out on the MTS Axial/Torsion servo hydraulic testing machine. Findley and McDiarmid multiaxial criterion with Palgren-Miner summation rule have been used for fatigue life-time estimation of the tested specimens

Experimental Quantification of the Fatigue Stress Concentrator on Mig Butt Welded S355 Steel Specimen

Joining components by welding is the most widespread method of joining for metal structures. For this reason, fatigue strength assessment of welded joints is of great interest to engineers involved in structure design. The welded joint itself can be considered a notch composed of a technological (inner deffects and material inhomogenities) and a geometrical (surface irregularities) part. Due to stress and strain concentration, such a notch decreases fatigue endurance of a welded construction. This paper shows experimental quantification of the fatigue stress notch factor for butt welded joints manufactured by MIG technology

Fatigue strength assessment of bridge dilatation shutter in real operation

In general, the bridge dilatation shutters and their components are dynamically loaded structures and so, the fatigue strength for such bridge joints should be analytically evaluated during design process. Due to difficulties arisen in calculation of acting forces on individual components the bridge shutters were assessed in a real operation. In the article, there will be presented results and diagrams obtained from direct measurements of the time depending strain i.e. stress processes in the critical points for that bridge dilatation joint. In addition, the results obtained from measurements and fatigue strength evaluation will be also confronted with testimonials based on applications of standards

Multiaxial cycle counting method for non-proportional multiaxial variable loading signals based on modified maximal shear stress

One of the most challenging task in field of multiaxial fatigue is fatigue lifetime estimation of components loaded with multiaxial non-proportional variable amplitude loading. While this task consists of multiple smaller problems, one of the most crucial ones is loading cycles identification (and extraction) for future use with multiaxial damage criterions. By now, several cycle counting methods have been proposed for multiaxial loading conditions. The most wildly accepted methods are Bannantine-Socie’s method and Wang-Brown’s method (which has been later modified by Meggiolaro and Castro). The aim of this paper is the comparison of newly developed method with Bannantine-Socie’s method and Wang-Brown’s method. The new cycle counting method is based on cycle identification in relative maximum shear stress histories (calculated from multiaxial loading histories). The extracted data than composes part of each loading channel of multiaxial loading histories corresponding to identified loading cycle. The comparison of chosen methods has been done by using data sets created by authors as well as using real measured data from real operation

Anthropometric outcomes of children and adolescents using telehealth with weight management interventions compared to usual care: a SR and MA

NEL BAT Scoring CriteriaPRISMA ChecklistSearch StrategyStata Data for Meta-analysis - BMI z-scores TH compared to usual careTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV